water creatures can fight each other even if neither is amphibious.
git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@8159 c06c8d41-db1a-0410-9941-cceddc491573
EXGDJN7TT5T6ONY56PTEWSZT4KDH7D3GGFE5FH52MACTOSNG23WAC XXXXXXXXXXXXXXXXXENDMAPNAME: arena_poolTAGS: arena_pool no_mons_genMARKER: A = feat: stone_stairs_up_iMARKER: B = feat: stone_stairs_down_iMARKER: O = feat: escape_hatch_upSUBST: A = ., B = ., O = .SUBST: . = WORIENT: encompassMAPXXXXXXXXXXXXXXXXXX...............XX.......B.......XX...............XX...............XX...............XX...............XX...............XX.......O.......XX...............XX...............XX...............XX...............XX...............XX.......A.......XX...............X